Cycloolefin copolymer composition

Abstract

Disclosed is a cycloolefin copolymer composition (C) obtained by copolymerizing an alpha -olefin of two or more carbon atoms (a) and a specific cycloolefin (b) in the presence of an aromatic ring-containing vinyl hydrocarbon/conjugated diene copolymer or a product of hydrogenation thereof (A) which has an intrinsic viscosity ( eta ) of 0.5 to 5.0 dl/g; at least one glass transition temperature (measured by DSC) of lower than 15 DEG C.; polymerizable carbon-to-carbon double bonds in an amount of 2 to 150 in terms of iodine value; and a refractive index nD(A) of 1.50 to 1.65. In the composition (C), the component (A) is contained in an amount of 1 to 40% by weight, and a difference DELTA nD between the refractive index nD(A) of the component (A) and a refractive index nD(B) of a cycloolefin copolymer component (B) obtained by copolymerizing the alpha -olefin (a) and the cycloolefin (b) in the absence of the component (A) is not more than 0.015. The cycloolefin copolymer composition is excellent in impact resistance, transparency and heat resistance.

What is claimed is: 
     
       1. A cycloolefin copolymer composition (C) obtained by: copolymerizing (a) an α-olefin and (b) a cycloolefin represented by the following formula (I) ##STR10## wherein n is 0 or 1,   m is 0 or a positive integer,   r is 0 or 1,   each of R 1  to R 18 , R a  and R b  independently represent a hydrogen atom, a halogen atom or a hydrocarbon group, provided that R 15  to R 18  may mutually bond to form a monocyclic or polycyclic ring structure which may contain a double bond, and a combination of R 15  and R 16  or a combination of R 17  and R 18  may form an alkylidene group, or by the following formula (II) ##STR11## wherein each of p and q is 0 or an integer of 1 or greater,   each of m and n is 0, 1 or 2,   each of R 1  to R 19  independently represents a hydrogen atom, a halogen atom, an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, an aromatic hydrocarbon group or an alkoxy group, provided that a carbon atom with which R 9  or R 10  bonds and either a carbon atom with which R 13  bonds or a carbon atom with which R 11  bonds may bond with each other directly or through an alkylene group having 1 to 3 carbon atoms and that, when n=m=0, a combination of R 15  and R 12  or a combination of R 15  and R 19  may mutually bond to form an aromatic monocyclic ring or aromatic polycyclic rings,   in the presence of component (A) a blend of a styrene/(ethylene/propylene)/styrene block copolymer and styrene/butadiene/styrene block copolymer, wherein the weight ratio of said styrene/(ethylene/propylene)/styrene block copolymer to styrene/butadiene/styrene block copolymer is 42/58 to 58/42,   the component (A) having an intrinsic viscosity (η), as measured in decalin at 135° C., of 0.5 to 5.0 dl/g, at least one glass transition temperature (Tg), as measured by DSC, of lower than 15° C., polymerizable carbon-to-carbon double bonds in an amount of 2 to 150 (g-iodine/g-polymer) in terms of iodine value, and a refractive index n D  (A), as measured at 25° C., of 1.50 to 1.65; wherein the copolymer composition (C) contains 1 to 40% by weight of the component (A), and a difference Δn D  is not more than 0.015, where Δn D  is |n D  (A)-n D  (B) |, n D  (A) being the refractive index of component (A) and n D  (B) being a refractive index of a cycloolefin copolymer component (B) obtained by copolymerizing said α-olefin (a) and said cycloolefin (b) in the absence of said component (A).